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US4354774A - Method and apparatus for the restrained and flame-retardant laying of electric cables - Google Patents

Method and apparatus for the restrained and flame-retardant laying of electric cables Download PDF

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Publication number
US4354774A
US4354774A US06/161,581 US16158180A US4354774A US 4354774 A US4354774 A US 4354774A US 16158180 A US16158180 A US 16158180A US 4354774 A US4354774 A US 4354774A
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US
United States
Prior art keywords
duct
cables
elements
supports
adjacent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US06/161,581
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English (en)
Inventor
Giuseppe Bianchi
Giovanni Gussoni
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pirelli and C SpA
Original Assignee
Industrie Pirelli SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Industrie Pirelli SpA filed Critical Industrie Pirelli SpA
Assigned to SOCIETA' PIRELLI S.P.A., A COMPANY OF ITALY reassignment SOCIETA' PIRELLI S.P.A., A COMPANY OF ITALY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: INDUSTRIE PIRELLI S.P.A.
Application granted granted Critical
Publication of US4354774A publication Critical patent/US4354774A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G3/00—Installations of electric cables or lines or protective tubing therefor in or on buildings, equivalent structures or vehicles
    • H02G3/02—Details
    • H02G3/04—Protective tubing or conduits, e.g. cable ladders or cable troughs
    • H02G3/0406—Details thereof
    • H02G3/0412—Heat or fire protective means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G9/00—Installations of electric cables or lines in or on the ground or water
    • H02G9/04—Installations of electric cables or lines in or on the ground or water in surface ducts; Ducts or covers therefor
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
    • H02G9/00—Installations of electric cables or lines in or on the ground or water
    • H02G9/08—Installations of electric cables or lines in or on the ground or water in tunnels

Definitions

  • the present invention relates to methods and apparatus for the restrained and flame-retardant laying of electric cables.
  • the present invention relates to methods and apparatus for laying electric cables in which the flame-retardent protection is obtained by arranging the cables inside a duct of rigid and non-flammable material and in which the restraining is obtained by anchoring the duct to a flat bottom and filling said duct with sandy materials.
  • relaxed laying refers to the laying of a cable in such way as will prevent any change in the length of the cable between its ends due to thermal variations.
  • One situation in which the present invention is particularly advantageous is where electric power cables for transmitting power at voltages on the order of 200-400 kV must be laid inside a tunnel (which can extend for several hundred meters) for connecting the transformers of a hydroelectric generating-station placed in a cavern with the sealing ends from which the overhead line start-off.
  • a tunnel which can extend for several hundred meters
  • the present invention may be found to be advantageous in all those cases where a restrained and/or flame-retardant laying is required.
  • a fixed structure comprising a duct of concrete with a generally U-shaped cross section is arranged along the tunnel.
  • Said duct is generally formed in place as a concrete casting, either in a seat excavated in the floor of the tunnel or on the floor itself.
  • the duct so obtained is anchored to the ground, at least through the action of its own weight and of the materials contained therein.
  • the electric cables are laid on the bottom of the duct, and the ends of the cables projecting from the extremities of the duct are secured to fixed supports by a clamping means.
  • the duct is filled with sandy materials according to known techniques and is completed with a concrete covering placed over the uppermost part of the duct. Said covering can be either cast in place or applied as a pre-fabricated slab.
  • said open duct can be formed by placing on the bottom a plurality of pre-fabricated elements instead of a unitary concrete duct cast in place.
  • said elements are placed into contact with each other and are rigidly joined to one another. Therefore, in this case, the duct is constituted, practically, by a single rigid block anchored to the bottom.
  • the duct is anchored to the floor of the tunnel, and therefore, it does not elongate.
  • the sand exerts against the walls of the cables friction sufficient to withstand the variations in length of the cables themselves.
  • the duct and the sand constitute a valid form of protection against fire and flames.
  • the present invention has, as one object, the avoidance of said drawbacks and at the same time to assure a suitable clamping of the cables, as well as good protection of the cables themselves against fire.
  • the apparatus comprising a duct of a rigid and non-flammable material, arranged around said electric cable or cables, anchored to said surface and filled with sandy materials, said duct comprising a plurality of elongated elements individually anchored to said surface and spaced from one another and comprising a flexible and non-flammable material for sealing the space between the elements along the outer perimeter of the space.
  • a further object of the present invention is a method for preparing an installation for a restrained and flame-retardant laying of cables comprising the following steps:
  • FIG. 1 illustrates schematically a restrained and flame-retardant cable installation in a tunnel extending from the zone in which there are transformers of a hydroelectric generating-station in a cavern and the zone in which there are sealing ends from which overhead lines start off;
  • FIG. 2 an enlarged cross-sectional view of a preferred embodiment of the installation.
  • FIG. 1 shows a cable C extending between the transformer TR of the generating-station CE and the sealing end T, from which the overhead line LA starts off.
  • the laying of only one cable C will be described, other cables, such as the cables C1 and C2 (FIG. 2) may be similarly layed.
  • the cable C passes through the tunnel G formed in the mountain M.
  • the elongated elements E1, E2, E3, etc. separated from one another by the spaces I1, I2, I3, etc.
  • Each of said elongated elements E1, E2, E3, etc. is comprised of support S1, S2, S3, etc., having a U-shaped cross section, and a slab P1, P2, P3, etc. which completely covers the uppermost portion of its corresponding support S1, S2, S3, etc. and is secured to the same.
  • Both the support S1, S2, S3, etc., having a U-shaped cross section, and the slab P1, P2, P3, etc. are constructed of a rigid and non-flammable material.
  • the slab P1, P2, P3, etc. are preferably made of concrete.
  • the elongated elements E1, E2, E3, etc. must be suitably anchored to the floor PG.
  • the elongated elements E1, E2, E3, etc. are constructed of concrete, their own weight and the weight of the materials contained therein constitute a sufficient anchoring means.
  • the elongated elements E1, E2, E3, etc. are aligned with one another to form a duct. Between said elements, there are spaces I1, I2, I3, etc. each of which is small with respect to the length of an elongated element E1, E2, E3, etc.
  • the elongated elements form a duct comprising individual elements spaced from and contiguous to other elements and movable, as may be required, with respect to each other.
  • the projecting ends of the cable C are secured to fixed sructures by clamping means ST1 and ST2.
  • the duct is filled with sandy materials according to known techniques.
  • the empty spaces I1, I2, I3, etc. are sealed along the outer perimeter with a flexible and non-flammable material M; preferably, in this case, the sealant may be silicone mastics or gummed-tape, each containing appropriate quantities of flame-retardant additives.
  • the sequence of the operations for restrained and flame-retardant laying according to the present invention is as follows: aligning and anchoring the supports having a U-shaped cross section in such a way so as to provide a space between each support (said supports can be made in place or can be pre-fabricated and thereafter placed inside the tunnel); sealing the spaces between said supports; laying the cable and clamping its ends; covering the cable with sandy materials; applying and securing a slab on each one of said supports and sealing the spaces between contiguous slabs.
  • FIG. 2 shows an elongated element E, which, according to a preferred embodiment of the present invention, has the cross-sectional shape of an isosceles trapezoid.
  • the elongated element E consists of a support S having a flat base and two sides inclined inwardly in the upward direction, and a slab P applied to the uppermost free ends and inside of said sides of said support S.
  • Said elongated element E shown with three cables C, C1, and C2, is filled with sandy materials SA which permit subsequent settling of the elongated element E without affecting the cables.
  • the characteristics of an elongated element can change to take into account the characteristics of the cables (dimensions, powers transmitted, coefficient of expansion, etc.) and of the zone where said restrained and flame-retardant laying must be prepared.
  • the elongated elements are of concrete and the cable voltage ranges from 200-400 kV
  • each of the elongated elements has a length of about 1 meter if the cables are provided with an aluminum protective sheath and has a length of about 0.5 meter if the cables are provided with a lead protective sheath.
  • the space between contiguous elongated elements is about 1 cm. in either situation.
  • the system representing the present invention permits the laying of cables in such a way so as to satisfy not only the required conditions of rigidity and non-flammability, but also to minimize the risk of serious damage to the duct and to the cables that would result from the mechanical stresses generated both inside and outside of said ductway.
  • the sub-division of the duct into a series of elements produces, as is easily understood, a significant improvement in the ease of preparation of the duct itself.

Landscapes

  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Laying Of Electric Cables Or Lines Outside (AREA)
  • Installation Of Indoor Wiring (AREA)
US06/161,581 1979-06-29 1980-06-20 Method and apparatus for the restrained and flame-retardant laying of electric cables Expired - Lifetime US4354774A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT23966A/79 1979-06-29
IT23966/79A IT1165136B (it) 1979-06-29 1979-06-29 Sistema di cavi elettrici

Publications (1)

Publication Number Publication Date
US4354774A true US4354774A (en) 1982-10-19

Family

ID=11211192

Family Applications (1)

Application Number Title Priority Date Filing Date
US06/161,581 Expired - Lifetime US4354774A (en) 1979-06-29 1980-06-20 Method and apparatus for the restrained and flame-retardant laying of electric cables

Country Status (9)

Country Link
US (1) US4354774A (pt)
AR (1) AR221277A1 (pt)
AU (1) AU529306B2 (pt)
BR (1) BR8003848A (pt)
CA (1) CA1146642A (pt)
ES (1) ES493264A0 (pt)
GB (1) GB2054280B (pt)
IT (1) IT1165136B (pt)
NZ (1) NZ194146A (pt)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4647251A (en) * 1982-09-22 1987-03-03 Cabletime (Installations) Limited Installation of communications cables
US5860768A (en) * 1995-11-15 1999-01-19 Asea Brown Boveri Ag System for transmitting electrical energy having at least one underground, high-voltage electrical conductor, and a method for producing such a system
EP1198045A1 (en) * 2000-10-11 2002-04-17 Swintex Limited Cable tray

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2048648B1 (es) * 1992-05-22 1996-09-01 Hernandez Jose Antonio Alonso Procedimiento para la instalacion de conducciones con cable de fibra optica incorporado.
GB2369728B (en) * 2000-11-21 2005-05-04 Level 3 Communications Inc Cable installation
GB0815311D0 (en) * 2008-08-21 2008-09-24 Jankel Paul Hydroelectric power generation system

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1923006A (en) * 1930-07-23 1933-08-15 Commercial Shearing Tunnel liner
US2355966A (en) * 1942-05-20 1944-08-15 Universal Zonolite Insulation Underground insulated pipe system
US2773512A (en) * 1955-06-14 1956-12-11 Morris S Burk Method of installing underground heating pipe systems
US2862367A (en) * 1956-09-27 1958-12-02 Silverstein Abe Precast cable trench
US2972968A (en) * 1956-11-21 1961-02-28 Thomas D Stafford Method of insulating and protecting pipe
US3427812A (en) * 1966-07-13 1969-02-18 Chance Co Ab Method and apparatus for anchoring offshore pipelines
US3582533A (en) * 1969-09-16 1971-06-01 Ite Imperial Corp Underground transmission system employing bare conductors supported by electrical insulating foam
US3675432A (en) * 1971-01-28 1972-07-11 Phillips Petroleum Co Pipeline construction

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1923006A (en) * 1930-07-23 1933-08-15 Commercial Shearing Tunnel liner
US2355966A (en) * 1942-05-20 1944-08-15 Universal Zonolite Insulation Underground insulated pipe system
US2773512A (en) * 1955-06-14 1956-12-11 Morris S Burk Method of installing underground heating pipe systems
US2862367A (en) * 1956-09-27 1958-12-02 Silverstein Abe Precast cable trench
US2972968A (en) * 1956-11-21 1961-02-28 Thomas D Stafford Method of insulating and protecting pipe
US3427812A (en) * 1966-07-13 1969-02-18 Chance Co Ab Method and apparatus for anchoring offshore pipelines
US3582533A (en) * 1969-09-16 1971-06-01 Ite Imperial Corp Underground transmission system employing bare conductors supported by electrical insulating foam
US3675432A (en) * 1971-01-28 1972-07-11 Phillips Petroleum Co Pipeline construction

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4647251A (en) * 1982-09-22 1987-03-03 Cabletime (Installations) Limited Installation of communications cables
US5860768A (en) * 1995-11-15 1999-01-19 Asea Brown Boveri Ag System for transmitting electrical energy having at least one underground, high-voltage electrical conductor, and a method for producing such a system
EP1198045A1 (en) * 2000-10-11 2002-04-17 Swintex Limited Cable tray

Also Published As

Publication number Publication date
AU5959380A (en) 1981-01-08
GB2054280B (en) 1983-03-02
GB2054280A (en) 1981-02-11
IT7923966A0 (it) 1979-06-29
ES8104657A1 (es) 1981-03-16
IT1165136B (it) 1987-04-22
NZ194146A (en) 1983-11-18
AU529306B2 (en) 1983-06-02
CA1146642A (en) 1983-05-17
BR8003848A (pt) 1981-01-13
ES493264A0 (es) 1981-03-16
AR221277A1 (es) 1981-01-15

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AS Assignment

Owner name: SOCIETA' PIRELLI S.P.A., PIAZZALE CADORNA 5, 20123

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:INDUSTRIE PIRELLI S.P.A.;REEL/FRAME:003847/0084

Effective date: 19810101

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Free format text: PATENTED CASE